A highly selective mitochondria-targeting fluorescent K(+) sensor

Angew Chem Int Ed Engl. 2015 Oct 5;54(41):12053-7. doi: 10.1002/anie.201506038. Epub 2015 Aug 21.


Regulation of intracellular potassium (K(+) ) concentration plays a key role in metabolic processes. So far, only a few intracellular K(+) sensors have been developed. The highly selective fluorescent K(+) sensor KS6 for monitoring K(+) ion dynamics in mitochondria was produced by coupling triphenylphosphonium, borondipyrromethene (BODIPY), and triazacryptand (TAC). KS6 shows a good response to K(+) in the range 30-500 mM, a large dynamic range (Fmax /F0 ≈130), high brightness (ϕf =14.4 % at 150 mM of K(+) ), and insensitivity to both pH in the range 5.5-9.0 and other metal ions under physiological conditions. Colocalization tests of KS6 with MitoTracker Green confirmed its predominant localization in the mitochondria of HeLa and U87MG cells. K(+) efflux/influx in the mitochondria was observed upon stimulation with ionophores, nigericin, or ionomycin. KS6 is thus a highly selective semiquantitative K(+) sensor suitable for the study of mitochondrial potassium flux in live cells.

Keywords: BODIPY; fluorescent probes; ion channels; mitochondria; potassium.

Publication types

  • Research Support, N.I.H., Extramural

MeSH terms

  • Boron Compounds / chemistry*
  • Cations, Monovalent / analysis
  • Cations, Monovalent / metabolism
  • Cell Line
  • Fluorescent Dyes / chemistry*
  • HeLa Cells
  • Humans
  • Microscopy, Fluorescence / methods
  • Mitochondria / metabolism*
  • Optical Imaging / methods
  • Potassium / analysis*
  • Potassium / metabolism
  • Potassium Channels / metabolism


  • 4,4-difluoro-4-bora-3a,4a-diaza-s-indacene
  • Boron Compounds
  • Cations, Monovalent
  • Fluorescent Dyes
  • Potassium Channels
  • Potassium